Yahoo has apologised for an outage to its Yahoo Mail service that has lasted since Tuesday morning UK time, with some users still apparently experiencing difficulties.

"We are very sorry for recent difficulties with Yahoo Mail," Jeffrey Bonforte, Yahoo's SVP of communication products wrote in a company blog post. "Some of our users have not been able to access their mail since 10.27pm PST on Monday night, due to a hardware problem in one of our mail data centres.

"The issue has been harder to fix than we originally expected. We have dozens of people working around the clock to bring it to a resolution."

It must have been much harder than they thought, because 12 hours later -- 7.15am UK time -- it still wasn't completely fixed.

"The affected servers have been up and running for over six hours and we've already delivered over 30 per cent of messages sent during the outage," an update on the Yahoo help site said. "We expect all emails to be delivered by tomorrow afternoon. Some users may still have trouble accessing their accounts but we are working through the night on this and will post again in the morning Pacific Time with the latest updates."

That means an update should be coming in the next few hours, with all emails delivered by the early hours of tomorrow morning UK time.

Some users may still have trouble accessing their accounts. We're working through the night on this. See http://t.co/U66mUNtEvO for more.

Have you been able to access your Yahoo Mail today? Has the outage caused any problems for you? Would this make you consider a different provider? Mail me a comment below, or over on our zero-downtime Facebook page.